Saw and key



Mmh v17, 1931.

T. F. BARRY E1' AL SAW AND KEY Original Filed May 31, 1929 INVENTORS ATToRls/Ex/.s`

Patented Mar. 17, 1931v narran Sfmlll-s SAW AND KEY Original application filed May 31, 1929,

'i' l" l 1929.-*S'erial' This invention provides a novel tubiilar saw, for' use in 'cutting button' blanlsffiloni shells and' the like, 'acollet `for 'positioning and holding such' saw lin proper shape' and "ondition for use;l and'nieansior `securing the sa'w-'in-thecollet. Thisapplication is a division of our application rfilleflll/lay 31,1929, Serial No. 367,436.

.Inthe'manufacture of so-called pearl but-- Lons the button blanks are ont -from the-:shells by ineans'of tnbularsaws. In orderthatour invention may be clearly understood it should be' notedthat atV present there are in eonnnon use'two types oi' saws, to Wiltyaf solid `tubular Ysaw, -`and a'split'tubular 'saw made o f'sheet steel bent into tubular forni. i i he 1solid tubular saw is inadebyboring out a eylindric piece of high' speed steel,'re'aniingthejbore to a certain size,a'nd turningithe saw to a certain eX- Lerior t diameter. To properly 'fharden'i and tenipersueh'saw it must be heated within a na'rrow temperature range, and jto a lower degree, than'is generally used for tools `made froinzhigh speed steel', for ifzhardened only slightly too'hard it is not iirstfclassyand-if hardened at slightly too low` afheat its Vefficiency will lie-'lowered accordingly. .After hardening, the saw'is,softened'(ti'o1n the tile hard onditionobtained by correct hardening bytenipering) -to'l a poin't where'theteeth can be tlled,and-tlienbui-red, upset for swagehto provide clearancein cutting. 'i-Saws'inade'troin high speed steel are not duct-ile after heat treatment and therefore their teeth (even though soft enoughto'lbe easily `filed) cannot be -set to provide the required clearance.; butgit properlytreated and' tempered' soit-"enough, canbe burred. It the initial hardeningfwaseffected at say aheat ot' only Q00 fF.,-,too-highl, then-*the jburr ldeveloped `or pnt on'-\vlienusing -will bey brittle, and after a few-buttons havebeen cnt the sawV will'no longer have the necessary inside yand ou'tsideclearance; and this fault cannotbe corrected bytempering. iAlso if the initial 'hardening Wase-li'ected ataheat say only QOO'too'lom'which frequently happens, the Y sawwill be toov sott and the-burrwill quickly wear ot and the' saw lack clearance.

"The solid tube'saws' niustgbegboredinside f Serial No. 367,436. Divided andithis application filed August 20,

and ground outside to a definite size, Which :involves a'large waste oi' steel, and l'nakes saws are teinperedabout as hard'as an ordinary wood cnttin'g'haiid saw.' The average selling-price of such saws is about -10 cents each. Thesesplitsteel'saws whilelow in price are costly-to use because they require such frequent sharpening and settingvtha't the consequent' loss of time for such operations and the wear on tiles flessensthe' operators earnings.v i Y' If a saw made froinhigh speed steel is teinpered soft enough to perniit setting the teeth its hardness isreduced to such an extent that ter'y little vif any cnttingcan be done. To illustrate, it a button saw is made from tungsten hack saw steel '(such hack -`saw teeth being setbefore the saw is hardenedand when properly heat treated will saw iron and steel), and-after hardening'is'softened to a degree that will permit the setting of the teethfor clearance, the teeth 'Will be so soft that they will only cut about 'four blanks at a sharpening. A sawinade'ifroni high speed steel or other alloyed-steels would act-.similarlytothehack sawV steel just describedf'I Many steels, othervlthan the varieties above 1nentioned,ilhave been tried forbutton'cutting saws and many elorts havebeenY made for years to producebet't'er saws; but up to the present inventionfn'oone has been able to producea saw superiortoor niore eliicient than the solid tubular high speedsteel saws andthe tubular vsheet steel saws hereinbefore described@ V' i `f our presentdinvention we provide a Cil novel tubular saw made from a special high speed sheet steel the teeth of which can be quickly heated, set while heated, and will be iile hard when cool. Our novel saw is free from the defects of and overcomes the objections to, the solid tubular saws and split tubular saws heretofore referred to, and can be easily setand sharpened as hereinafter explained, and is greatlyV superior in cutting qualities and durability. Our invention also provides means for holding the saw in shape while in use. f

ln the accompanying drawings weihave shown one practical embodiment of the invention and will describe the same with reference thereto, and summarize in the claims the essential features of the invention and the novel features of construction and novel combinations of parts for which protection is desired.

In said drawings:

Fig. 1 is a part side elevation and part sectional view of part of a simplebutt-on sawing machine equipped with our improvedl saw and collet.

Fig. 2 is a side view and Fig. 3 an end view of the saw.

Fig. 4 is a. part side and part sectional view of the collet and Fig. 5 is an end view of such collet.

Fig. 6 is an enlarged detail View of the key.

F ig. 7 is an enlarged transverse section of the collet and saw.

Fig.v 8 is a detail view of the toothed end of thesaw.

lThe saw l is made from special analysis high speed steel, which when in sheet form and heated to red, heat can be readily shaped. A suitable piece of such steel is heated and bent into tubular form slightly tapered to leave a V tapered opening la (Figs. 2 and 3) between the meetingvedges of the split. The smaller end of the saw is the cutting end, andthe larger end thereof is the discharge end, .the taper permitting the cut blanks to readily pass through the saw.

Such saw isr secured inA a suitable holder or 'collet 2 and its teeth subjected to the action of an electric current of sutlicient intensity to heat the teeth to the correct hardening heat at which temperature the teeth are soft; the saw teeth are then disengaged from the heating device and immediately engaged 'ith a setting 'die by which .the hot teeth are accurately setr; then the saw is withdrawn from the setting die, andthe teeth quickly cool in the air, and in so .doingbecome tile hard. and are ready'for use. y

The teeth can be .heatedand set by the method and apparatus described iny our companion application, tubular saw-heating and setting machine, filed May 31, 1929, Serial No. 367,434. The teethl canv be easily heated 'hy this apparatus to the correct temperature for hardening high speed steel, and can be readily set thereby while heated, and when the teeth cool and are no longer visibly red they will be iile hard. The saws so made and treated are exceedingly durable because of the special steel used; the short heating cycle; the relatively slow air cooling; and the hardness of teeth.

The collet 2 has an' internal tapered bore corresponding to the exterior diameter of the saw l, and aA longitudinal keyway 2d with which keyway the slot 1a in the saw should register. The collet, see Figs. 1 and 4, has an externally threaded portion 2a at one end,

van intermediate central portion of slightly less diameter than the threaded portion 2a, and a reduced tapered portion 2?) at the other end. The collet has an annular flange or collar 2c on its exterior intermediate the parts 2a and 2?). This collar might be made integral with the body of the collet as described in the application of Thoniias F. Barry filed December 4th, 1926, Serial No. 152,648. This collar is provided in one face with radial notches 2f for engagement with an indexing pawl as described in our companion application for button saw tooth grinding machine filed May 81, 1929, Serial No.. 367,435. The collar 2c is provided with a beveledsurface 2g on its inner end which is adapted to engage an opposed beveled surface 4g in the end of the head 4 of a spindle 4a of any suitable machine to which the saw is to be attached', an ordinary button cutting machine being indicated in the drawing. The threads 2a of the collet are coarse and slightly smaller than the internal threads in the head 4 with which the threads 2a in the collet engage with a loose fit, so that when the collet is screwed into the head the beveled surface 2g of the collar engaging the beveled surface 4g of the head will accurately center the collet and saw in theV head, the loose fit of the threads permitting this. Heretofore split tubular saws have been fitted into tapered bores in a collet and a tapered key entered inthe slot in the saw. The performance of a saw in cutting pearl buttons is greatly dependent upon the accuracy and care used in mounting the saw in the collet, which operation determines whether the saw will run true Cil or wobble, and therefore produce more or r less perfect blanks. Heretofore after the saw is inserted in a collet, a key and a pin (havinfr the same taper as the slot in the saw) was placed in the saw-and the key pinched against the pin by holding in a vise, and the collet driven down until tight on the saw. Then the collet and saw was driven into a tapered hole in the chuck head of the button cutting lathe. Then the assembly was revolved to enable the operator to determine if the saivwas properly aligned. lf not the machine was stopped and the collet tapped with a hammer to align the saw, and this pro- CTI cedure was repeated until the saw seemed to run true. Such pounding on the collet batters it and bulges in the bore under the fiange.

and frequently makes it necessary to re-ream the bore-and this frequently causes same to be out of center.

To obviate allY the above numerous difficulties, we provide the collet with an internal longitudinal keyvvay or groove 2d in which is inserted a slidable key 3. The keyway is breached in the improved collet in line with the face of some one notch 2f in the collar to assure the cutting of full size teeth at each side of the split in the saw when grinding the The key way is broached in definite relationship to the notches which of course determine the position and number of teeth and the face of one tooth is always on one edge of the saw at the split. The key 3 has a base portion that fits the groove in the collet anda projecting rib 3a the sides of which are tapered to fit or engage the tapered opening la in the saw. 4

The rib 3a is preferably tapered at each end for about 1% inches as at 3c (Fig. 6). This short'taper is sufficient to insure a close fit within the tapered splitopening in the saw,

(which might not be the case were the taper to extend the full length of the key) and such short taper insures a complete rounding up of the toothed end of the saw, which projects out of the collet.

With the improved collet it is not necessary to file out the saw and it is not necessary to file the improved key. All that is necessary to mount the improved saw in the improved collet is to insert the saw into the collet from the rear or large end of the bore with the tapered split in the saw approximately in line with the straight groove 2d in the collet. Then insert the key 3 into the groove 2d so the first entere-d tapered end of rib 3a engages the tapered opening in the saw. The key as it enters brings the tapered split in the l saw in line with the groove, and when pressed in wedges the tapered saw outwardly against the bore in the collet and holds the saw firmly therein. y

The different widths of the tapered pori tions 3c of the key rib enables one key to be used with saws having splits slightly differing in width, which differences are caused by slight unavoidable variations in the thickH ness of the hot rolled tool steel used for the saws.

" are ground in the saw.

In operation the saw runs in a counter clockwise direction and we have found that the outwardly set teeth in a split tubular saw are under greater strain, and the two most severely stressed teeth are those adjacent the split. v"The.trailing tooth at the ,splitintlie saw tends to spread out and cut a. 'larger groove, and such tendency is aggravated if such tooth is set out, and is minirn'izedzif such tooth isset in. 4 A'llherefore.,we'inake theteeth 1 1t, le, 4=F ig. 2, atr each side of the split in fthe saw both -full teeth and set iboth' inwardly whereby they `are relieved of considerable strain, and Vbreakage of such teeth is practically eliminated, and `the .will run more truly .than lif such teeth areset ,alternatelyl in and out. y

After the lteeth `have ybeen ground on vthe sav.' the collet holding Kthe saw' is .removed from ,the saw ltooth grinding machine vand u i placed ingthehardening and setting `machine '2. In combination with a collet 1:having a l tapered bore to receive a'splittaperedltubular saw andfa longitudinal parallel Asided slot-in the bore; ofia'reversiblekeyfhaving a vparallel side-d base to engage thel slot in the collet, and a projecting rib tapered xat its f' end' so fit.' be entered` into A the split in the'saw 4toeXpand it 4inthe collet when thekeyisenteredfintothe slot.

lIncombinatioira collet having atapered bore to receive',alsplittapered tubular saw, and a'lolngitudinalslotinthe bore; and a reversiblefkeyhaving a baseiitted in this slot and a projecting rib tapered at each end so that either end can be entered into the split in the saw to expand the saw in the collet when the key is driven into the slot.

Il. In a tubular saw cutting machine, a collet having a bore adapted to receive a split tubular saw, and a straight parallel sided keyway in said bore; and a. reversible key comprising a base having its sides parallel to fit thel parallel sided keyway, and a projecting rib on the base adapted to be interposed between the edges of the split in the saw, said rib having each end tapered so that either may be entered into the split.

5. A key for the purpose specified comprising a body portion of uniform width, and a raised longitudinal rib on one face of the body, said rib having a tapered end and the side edges of its major portion parallel.

6. A key for the purpose specified com? prising a body portion of uniform width,

and a raised rib on one face of the body having each end tapered and'the side edges of the intermediate portion parallel.

7. A reversible key for the purpose specified comprising a base adapted to engage a slot in a saW holding collet, and a longitudinal raised rib on one face of the base having each end tapered so that either end may be entered into a saw in the collet, the intermediate portion of the rib having parallel sides.

8. A reversible key for the purpose speoilied having a straight body portion with parallel sides adapted to fit a straight parallel sided lteyWay in a saw holding Collet, and having a longitudinal rib on the base having each end tapered so that either end may be entered between the meeting edges of a saw y in the collet andthe portion of the rib interinediate the' tapered ends thereof having parallel'sides. f

9. In combination, a Collet having a bore provided With a keyway, a split tubular tool in said bore, and a reversible key having a body portion of uniform -Width litting the keyvvay and having a longitudinal rib adapted to have either end entered between the meeting edges of the tool, said rib portion having each end tapered and its sides intermediate the tapered ends parallel.

l0. A tubular button cutting saW having teeth of high speed file-hard steel maintained set by their file hard condition.

l1. A savv as set forth in the neXt preceding claim, having a full inwardly set tooth at each side of the split therein, for the purvpose specified.

l2. A tubular button cutting saw of high speed file-hard steel with its teeth set and maintained set by the ile hard condition as a eounterbalanoing effect .to the distortional "stresses set up by the setting operation.

THOMAS F. BARRY. LEONARD BOWEN. 

